The present invention relates to a time switching circuit used in a line exchange for exchanging n data strings in a set of data strings and between sets of data strings.
When data exchange, e.g., exchange of n (n is a constant greater than 2) data strings is to be performed in a set of data strings and between sets of data strings, a time switching circuit is used. Time switching circuits of this type are classified into a single time switching circuit in which n data strings are time-divisionally multiplexed, and data are exchanged by one data memory and one address control memory, and a parallel time switching circuit in which data are exchanged using n.times.n data memories and n address control memories.
When a line capacity is to be increased in a conventional time switching circuit, the speed of data subjected to line exchange must be increased to increase the degree of multiplexing, or the parallel time switching circuit must be used.
However, when the single time switching circuit is used, the operation speed of the switching circuit is disadvantageously increased in proportion to a data speed and the number of line exchange data strings.
On the other hand, when the parallel time switching circuit is used, the total size of data memories is increased in proportion to the square of the number of line exchange data strings. In addition, when a line capacity is to be increased, the total size of the data memories and the like must be increased. In either case, a circuit arrangement itself must be changed, and the line capacity cannot be flexibly increased.